could be cause they have less stuff in clearview to render... so less stuff in map = more performance when its not culled out

u can try simple test that shows this, get your favorite video game engine start adding something like simple cube at some point your framerate will crash. the exact point depends on the game engine, your gpu,cpu,memory,storage, your drivers, ect...

there is just so much that can be drawn at a time and so much that can be batched together and rendered in a single point beyond that its like very low framerate

the same with textures. if u have lots of objects with different textures not in a batched texture atlas at some point your framerate will crash too cause it just cant get the textures in fast enough. so video games take a bunch of textures and batch them together in an atlas. at some point you cant stick any more and at some point you have too many atlases / textures that have to be stream into video card to render a frame. the exact amount and size ect depends again on your game engine, your gpu,cpu,memory,storage, your drivers, ect...

so this could just be a sweet spot for some. others with let say laptop that cant move / crunch things fast enough, ect still cant deal with it and will be getting horrible framerate cause of the size of the map, the complexity of the level, the number of objects in it, the draw distance, the number of players, the numbers of npc, ect...